Typically, a bicycle has front and rear wheels which are rotatably supported on bearings disposed within a hub. Spokes extend from a pair of spaced flanges on the hub for supporting a rim upon which a tire is mounted. A shaft is typically fixed to a bicycle frame and passes through a central passage in the hub. The shaft has bearings disposed in-board of threaded ends which allow mounting the wheel to the frame. The rear wheel hub differs from the front wheel hub as it typically supports various gears which function as part of a drive system. The gears may either provide a single speed or multiple speed settings.
Recently, efforts have been made to produce more efficient bicycle wheels particularly seeking reduced weight and improved aerodynamics. For example, there is a trend towards the use of exotic composite materials and alloys for bicycle construction. However, such materials are quite expensive and components made from such materials are often difficult to repair.
One problem in bicycle wheel design involves reducing the aerodynamic drag caused by round spokes which extend from a conventional wheel hub. Such spokes extend from the sides of the narrow rim/tire combination and thus effectively increases the aerodynamic width of the wheel, causing increased drag. One solution is to use a front radially laced wheel with a standard wheel hub having a conventional flange spacing of about 55-70 millimeters. In a non-radial laced wheel, the spokes crossover each other in proximity to the hub and typically two spokes are in contact at the crossover point. The overlapping spokes increase the front profile of the wheel. In a radial laced wheel, there is no crossover or touching, exhibiting an aligned profile. The wheel may also have flattened spokes or oval spokes instead of round spokes, with the bladed or oval spokes offering less wind resistance than round spokes.
Another type of bicycle wheel uses either a segmented or whole disk instead of round spokes to reduce front wheel drag. These wheels are typically made of carbon fiber reinforced composite materials and are very expensive. They are also difficult to repair. While providing a more aerodynamic front profile than standard wheels, the whole disk wheels additionally are considered unstable in cross winds.
In a spoked wheel, there has been no effort to alter the spacing of the wheel hub flanges. If the flanges could be brought together with a narrower spacing, the angle of the wheel spokes could be made more vertical to reduce wind drag. However, if this is done, there is a perceived loss of lateral stiffness which is a measure of the force required to deflect the rim to the side, which may make the wheel more likely to collapse from side loads. Rear wheels typically are asymmetrical in terms of flange orientation due to the provision of multi-speed gear clusters. According to one authority, by moving the outer asymmetrical flange closer to the center to improve the balance in spoke tension and reduce offset, i.e. the differences in spoke tension due to the asymmetrical orientation of the flanges, would improve the balance of spoke tension but only at the expense of reducing lateral strength on both sides of the wheel. Consequently, it is commonly believed within the industry that if the flanges were moved closer together, lateral strength on both sides of the wheel would be reduced, which is considered unacceptable.